In this work, the bubble points of some selected synthetic C6+ mixtures were measured in the presence of carbon dioxide. In all the systems, the composition of carbon dioxide was kept about 25 mol %. Measurements were carried out in the Cailletet apparatus within a temperature range of 312 K to 470 K. In addition, the ability of the Peng-Robinson equation of state (PR EOS) in correlating the phase behavior of CO2 + C6+ fractions was investigated, by correlating the bubble points of experimented systems using this equation of state. To increase the accuracy of the correlations, suitable binary interaction parameters between each component of the C6+ mixture and carbon dioxide were determined, which minimized the difference between correlated and experimental bubble point pressures. Average absolute deviations between experimental and predicted data are less than 2.1% in all the systems.